This research proposes to construct and analyze a longitudinal model of the relationship between family composition and the labor force participation of married women. The model will be estimated for two separate cohorts of women drawn from the National Longitudinal Surveys. Family composition is conceptualized as a dynamic set of variables including the number, ages, and spacing of children. The dimensions of labor force participation to be included in the model are labor force experience, the intensity of labor force participation, and the nature of the occupational task. The second stage of the analysis will address the manner in which the parameters of the model are influenced by a set of exogenous variables. Once the model has been estimated for the two cohorts the parameters will be utilized as dependent variables hypothesized to be influenced by the exogenous variables. The respondent's education, the availability of childcare, the family's economic well-being, and the familial context are all thought to affect the nature of the basic relationship between family composition and labor force participation as defined in the model. The successful completion of this research will generate one model of the reciprocal causal relationship between family composition and labor force participation from a national sample of women who have completed their families and another model from a sample of women who are in the process of family building. The inclusion of the exogenous variables will provide additional information on the specific conditions under which the relationship takes various forms.